How to find multiple objects in List without loop?

Question

C++ / C#

There is such a pool of objects . Let's say 30 objects in it
public List<Enemy> enemyPool = new List<Enemy>();

public class Enemy
{
    public int Id { get; set; }
    public int ParentRoomId { get; set; }
    public GameObject GameObj { get; set; }
}

There is a cycle

foreach (Enemy enemy in enemyPool)
            {
                if (amount > 0)
                {
                    if (enemy.ParentRoomId == 0)
                    {
                        enemy.ParentRoomId = roomId;
                        enemy.GameObj.transform.position = spawnPosition.position;
                        enemy.GameObj.transform.rotation = spawnPosition.rotation;
                        enemy.GameObj.SetActive(true);
                        amount--;
                    }
                }
                
            }

I need to find objects that have enemy.ParentRoomId == 0 . The foreach loop loops through the entire list. Is there a way to find a certain amount without a loop? And not just to find, but to perform a certain process on them with the help of science.

Answer 1

break or goto to exit foreach

Answer 2

I suspect you want something like this

enemyPool
  .Where(e => e.ParentRoomId == 0)
  .Take(amount)
  .ToList()
  .ForEach(e => 
  {
    e.ParentRoomId = roomId;
    e.GameObj.transform.position = spawnPosition.position;
    e.GameObj.transform.rotation = spawnPosition.rotation;
    e.GameObj.SetActive(true);
  });

If you really want to optimize with, then you can

count = 0;
for(vat i = 0; i < enemyPool.Count; i++)
{
  if(enemyPool[i].ParentRoomId  == 0)
  {
    count ++;
    if(count >= amount)
      break;
    enemyPool[i].ParentRoomId = roomId;
    enemyPool[i].GameObj.transform.position = spawnPosition.position;
    enemyPool[i].GameObj.transform.rotation = spawnPosition.rotation;
    enemyPool[i].GameObj.SetActive(true);
  }
}

Answer 3

It is not very clear what you need and most importantly why.
The cycle will be one way or another. The word "find" already implies a search of options. The loop can be hidden (Where from LINQ). It may not go through the entire array, but only until the required amount is found (we just exit the loop when we have found everything we need.
Without a loop, you can only add the necessary objects somewhere in advance. But in my opinion this is not what you need ...
You can of course sort the array by parentRoomId and take the first 3 elements - but sorting is also a cycle.

Answer 4

Maybe wrong, but List has a method called contains

Answer 5

It is forbidden. Either way, a cycle is required. The number of iterations can be reduced if the list is sorted. But why? You can shorten the code length. To do this, you need to use a loop wrapper, such as linq.